Inhibitory effect of hypoxia preconditioning on hypoxia/reoxygenation-induced apoptosis in cardiomyocytes

AIM: To study the role of hypoxia preconditioning (HP) in hypoxia-reoxygenation (HR)-induced apoptosis in neonatal rat cardiomyocytes and the possible mechanisms. METHODS: Cultured neonatal rat cardiomyocytes were divided into three groups: normal group, HP+H/R group and H/R group. Acridine orange (AO) staining was performed to detect morphological changes of apoptotic cells. Apoptosis rates of cardiomyocytes were detected by flow cytometry. Colorimetric assay was used to detect caspase-3 activity. Expression of Bcl-2 protein was detected by immunohistochemistry combined with computer image analysis. RESULTS: Apoptotic cells were detected by AO staining after hypoxia of 6 h followed by 3 h-reoxygenation. The hypodiploid apoptotic peak was detected by flow cytometry with the apoptotic rates of (29.7±5.4)%. A significantly reduced apoptotic rates of (7.8±1.3)% was detected in HP group（P＜0.01）. The caspase-3 relative activity of cardiomyocytes induced by H/R was 5.9±0.8, significantly higher than that of control group. HP markedly reduced caspase-3 relative activity to 2.6±0.5 in contrast with H/R group （P＜0.01）. Bcl-2 protein was positive in normal cardiomyocytes with an A value of 119.4±7.1. The A value of H/R group was 99.6±5.0, significantly lower than that in normal group （P＜0.01）. The A value of HP+H/R group was 126.5±6.2, significantly higher than that in H/R group（P＜0.01）. CONCLUSION: HP inhibits H/R-induced apoptosis of cardiomyocytes by improving the expression of Bcl-2 and reducing caspase-3 activity.     

Effects of adiponectin on reducing endoplasmic reticulum stress injury induced by hypoxia-reoxygenation in cultured rat neonatal cardiomyocytes

AIM: To investigate the effects of adiponectin (APN) on hypoxia-reoxygenation (H/R) induced endoplasmic reticulum stress injury in cultured cardiomyocytes. METHODS: Primary cultured cardiomyocytes were obtained from neonatal rats by enzymatic digestion method. The α-actin expression as molecular marker of the cardiomyocytes was observed by immunocytochemistry. The cells cultured for 72 h were used in the experiment and divided into groups randomly: control group, H/R group, APN+H/R (3 mg/L, 10 mg/L, 20 mg/L, 30 mg/L) groups. The morphological changes of the cardiomyocytes were observed under phase contracted microscope. The content of LDH was measured. The cardiomycocyte apoptosis was detected by flow cytometry. The expression levels of GRP78 and caspase-12 were examined by RT-PCR and Western blotting. RESULTS: The apoptotic rate was significantly increased in H/R group as compared to that in control group (68.20%±1.73% vs 0.73%±0.21%, P<0.05). The levels of LDH in H/R group were also significantly increased. Compared to untreated cells, the protein and mRNA levels of GRP78 and caspase-12 increased significantly in H/R cells. The APN preconditioning significantly reversed these changes. The indexes above improved obviously as compared to H/R group (P<0.05) in a dose-dependent manner. CONCLUSION: Hypoxia/reperfusion induces endoplasmic reticulum stress in rat cardiomyocytes. Adiponectin decreases the endoplasmic reticulum stress injury and plays a protective role by extenuation of cadiomyocyte apoptosis.     

Effects of leptin on hypoxia-reoxygenation induced apoptosis in human L02 cells and expression of Fas and FasL

AIM: To observe the effect of leptin (LEP) on hypoxia-reoxygenation induced apoptosis in L02 cells.METHODS: In the experiment, L02 cell injury was induced by hypoxic air (95%N2 and 5% CO2). The cultured L02 cells were divided into hypoxic 12 h group (IR group) alone, normal control group and the hypoxic plus leptin (100 μg/L, 200μg/L, 400 μg/L, 800 μg/L and 1 600 μg/L) treatment groups in vitro. Flow cytometry, terminal dUTP nick-end labeling (TUNEL) assay and fluorescent quantitative PCR were used to measure the changes of apoptosis in L02 cells and expression of Fas/FasL mRNA.RESULTS: (1) The percentage of L02 cells apoptosis and positive TUNEL cells significantly increased in IR group compared to control group (P<0.01). When L02 cells were treated with LEP, the percentage of cell apoptosis and positive TUNEL cells were decreased compared to IR group. (2) Compared to control group, the Fas/FasL mRNA expression significantly increased in IR group (P<0.01). When L02 cells were treated with LEP, the Fas/FasL mRNA expression decreased compared to IR group, the effect of LEP at concentration of 400 μg/L was obviously (P<0.05). CONCLUSION: LEP decreases the apoptosis of hypoxic-reoxygenation L02 cells by down-regulation of Fas/FasL mRNA expression in L02 cells.     

Effect of Shenmai injection on cardiomyocyte apoptosis after acute anoxia-reoxygenation

AIM: To study the effects of Shenmai injection on cardiomyocytes apoptosis after acute anoxia-reoxygenation (A/R) and the possible mechanism. METHODS: In this experiment, cultured cardiomyocytes isolated from neonatal rat were used. Model of myocardial anoxia-reoxygenation injury was produced by depriving oxygen for 5 min and then restoring oxygen for 15 min. The apoptotic cells was detected by flow cytometry to detect labbled Annexin V-FITC/PI. The intracellular calcium level was observed by laser scanning confocal microscopy markered Fluo-3/AM. RESULTS: In anoxia-reoxygenation group, the percentage of apoptotic cells and fluorescent intensity of intracellular calcium were both prominently higher than those in control group (P<0.01). The apoptotic rate in Shenmai injection group was notably less than that in A/R group and the intracellular calcium overload was also less obvious in Shenmai injection group than that in A/R group (P<0.01). CONCLUSION: Shenmai injection has notable effects on attenuating apoptotic rate after acute anoxia-reoxygenation in cardiomyocytes, which may be partly due to its alleviating intracellular calcium overload.     

Effects of T-cadherin on hypoxia/reoxygenation-induced apoptosis of cardiomyocytes from neonatal rats

AIM: To investigate the mechanism of cardiomyocyte apoptosis induced by hypoxia/reoxygenation (H/R) by silencing a new adiponectin receptor T-cadherin through adenovirus-mediated RNA interference. METHODS: The primary cardiomyocytes were isolated from neonatal rats and cultured for 72 h. The cardiomyocytes were randomly divided into control group, H/R group, APN+H/R group, Ad-T-cadherin-siRNA+APN+H/R group and Ad-HK (adenovirus negative control)+APN+H/R group. The transfection ability and efficiency were examined. The expression of T-cadherin at mRNA and protein levels was detected by RT-PCR and Western blotting. The apoptotic rate was analyzed by flow cytometry and TUNEL. RESULTS: High purity of neonatal rat cardiomyocytes was obtained by primary culture. After 48 h, over 90% of myocardiocytes were infected at MOI=100. The transfected myocardiocytes showed a low expression level of T-cadherin under normal physiological condition. Compared with APN+H/R group, the cell apoptotic rate significantly increased in Ad-T-cadherin-siRNA+APN+H/R group (P<0.05). Compared with H/R group, the difference was not statistically significant (P>0.05). CONCLUSION: Ad-T-cadherin-siRNA effectively infects myocardial cells in vitro and successfully reduces the expression of T-cadherin in myocardial cells. The inhibitory effect of adiponectin on H/R-induced cardiomyocyte apoptosis is attenuated by decreasing the expression of T-cadherin.     

Dengue virus type 2 induces apoptosis and expression of death receptor in hepatic veno-endotheliocyte ED25

AIM: To investigate apoptosis and the expression of death receptors of TRAIL,TNF and Fas on hepatic veno-endotheliocyte ED25 cell strain induced by dengue virus type 2(DV2).METHODS: Flow cytometric analysis was used to detect the number of apoptotic cells and the expression levels of TRAILR1-4 ，TNFR1-2，Fas on ED25 cells before/after DV2 infection.RESULTS: The numbers of apoptotic cells of ED25 increased after DV2 infection,there were only about 5.7%±1.2% of apoptotic cells before virus infection while there were approximately 27.3%±1.6% of apoptotic cells after virus infection.At the same time the expression level of Fas also increased,before virus infection about 44.3%±2.2% of ED25 cells expressed Fas while 63.0%±2.3% of ED25 cells expressed Fas after virus infection.CONCLUSION: DV2 infection can induce apoptosis of ED25 cells,and it suggests strongly that Fas/FasL may be involved in the apoptotic signal transduction.     

Effect of glycine liposomes on mitochondrial membrane potential and apoptosis in cultured cardiomyocytes

AIM: To observe the effect of glycine liposomes on the mitochondrial membrane potential and the apoptosis rate in cardiomyocytes induced by hypoxia/reoxygenation injury. METHODS: A cardiomyocyte injury model was established by using hypoxia/reoxygenation. DiOC6(3) as fluorescence molecular probe was used to detect the mitochondrial membrane potential in each group. The method of Annexin V associated with PI was used to detect the apoptosis ratio in each group. RESULTS: (1) The result of flow cytometry showed that the mitochondrial membrane potential of cardiomyocytes in H/R group was obviously lower than that in control group (P<0.01). The decrease in mitochondrial membrane potential in Gly-liposome group was the lowest, the percentage of cells about the part of hypofluorescence was (9.61±0.76)%, which was lower than that in glycine group (P<0.01). (2) The apoptosis rate of cardiomyocytes in H/R group was higher than that in control group (20.78±1.58)%,P<0.01. After the treatment of Gly-liposome, the apoptosis rate of cardiomyocytes was lower than that in glycine group (P<0.01). No difference in the apoptosis ratios between blank-liposome group and H/R group was observed(P>0.05).CONCLUSION: Glycine liposomes protect cultured cardiomyocytes against hypoxia/reoxygenation injury. Glycine liposomes produce the better protective effects than glycine.     

Expression and effect of miR-139-3p in apoptotic neonatal rat cardiomyocytes induced by hypoxia

AIM:To investigate the expression and clinical significance of microRNA-139-3p (miR-139-3p) in the apoptosis model of cardiomyocytes induced by hypoxia. METHODS:Under normal and hypoxic conditions, the expression of miR-139-3p in neonatal rat cardiomyocytes was detected by RT-qPCR. miR-139-3p inhibitor and miR-139-3p inhibitor negative control were transfected into the primary neonatal rat cardiomyocytes. The transfected cardiomyocytes were cultured in closed anoxic box (95% N₂ and 5% CO₂) at 37℃ for 12 h. Flow cytometry and Western blot were used to determine the apoptosis of cardiomyocytes. RESULTS:After hypoxia for 12 h, the expression level of miR-139-3p and the apoptotic rate of the cardiomyocytes in hypoxia group were significantly higher than those in normal group (P<0.05). Moreover, compared with the miR-139-3p inhibitor negative control group, the apoptotic rate of the cardiomyocytes was significantly decreased in miR-139-3p inhibitor group (P<0.05). CONCLUSION:The expression of miR-139-3p is signi-ficantly increased in apoptotic neonatal rat cardiomyocytes induced by hypoxia. Inhibition of miR-139-3p expression reduces hypoxia-induced apoptosis of cardiomyocytes.     

第27届国际园艺大会将于2006年8月13—19日在韩国汉城召开

由国际园艺学会和韩国园艺学会共同主办的第27届国际园艺大会将于2006年8月13～19日在韩国汉城召开(同期举办展览)。会议主题是“全球园艺:多样性与和谐”。会议组织委员会主席为韩国庆熙大学李政明(Jung MyungLee)教授,副主席为韩国汉城市立大学JeongSikLee教授和韩国汉城大学     

Effects of Tertram ethylpyrazine on expression of Fas/FasL mRNA in lung tissue with ischemia-reperfusion injury in rabbits

AIM: To study the expression of Fas/FasL mRNA in lung tissue with ischemia-reperfusion lung injury in rabbits and the relationship with the apoptosis,and to observe the effects of Tertram ethylpyrazine on them.METHODS: The pulmonary ischemia-reperfusion models in rabbits with occlusion of left pulmonary hilum for 1 h and then reperfusion 1,3,5 h respectively were used in this experiment.In TMP group,Tertram ethylpyrazine was intravenously dropped at dose of 60 mg/kg at 1 h before ischemia.The TUNEL technique was used to explore apoptotsis of pulmonary cells.In situ hybridization was performed on the rabbit lung tissue to assay the expression of Fas/FasL mRNA.RESULTS: Apoptosis of pulmonary cells was found in both IR group and TMP group.Compared with group IR,the apoptosis index (AI) was decreased obviously in group TMP (P<0.01).There was a significant positive correlation between the expression of Fas/FasL mRNA and the apoptosis of pulmonary cells (r₁=0.900,r₂=0.869,P<0.01).CONCLUSION: The activation of Fas/Fas-L system may contribute significantly to induce pneumocyte apoptosis in pulmonary ischemic injury.Tertram ethylpyrazine inhibits the activation of Fas/FasL system to decrease apoptosis in pulmonary tissue,which may protect the pulmonary tissues in ischemia injury.     

Effects of panax notoginseng saponins on pneumocyte apoptosis and Fas/FasL expression in rabbits with lung ischemia/reperfusion injury

AIM: AIM: To explore the relationship between apoptosis in the lung tissues and lung ischemia/reperfusion injury, and observe effects of panax notoginseng saponins (PNS) on apoptosis in lung ischemia/reperfusion injury. METHODS: Single lung in situ ischemia/reperfusion animal model was used. Eighty four Japanese white rabbits were randomly divided into control group (control), ischemia/reperfusion 1 h group (IR1h), IR3h, IR5h, Panax Notoginseng Saponins 1 h group (PNS1h), PNS3h and PNS5h. TUNEL, immunocytochemistry and in situ hybridization techniques were used to observe apoptosis and Fas/FasL expression in various phases of lung ischemia/reperfusion. RESULTS: Cell apoptosis in lung tissues were significantly high, Fas/FasL mRNA and its protein were up-regulated in lung tissues of lung ischemia/reperfusion injury compared with control (all of P<0.01). The PNS suppressed apoptosis as well as expression of Fas/FasL mRNA and its protein (P<0.05 or P<0.01, respectively). There was a significant correlation between expression of Fas/FasL protein, Fas/FasL mRNA and cell apoptosis (r=0.540，0.658，0.668，0.686；all P<0.01). CONCLUSIONS: Activation of Fas/FasL system and its initiating cell apoptosis of lung tissues may contribute to the pathogenesis of lung ischemia/reperfusion injury. The protective effects of PNS include suppressing the activation of Fas/FasL system and blocking apoptosis in lung tissues in lung ischemia/reperfusion injury.     

Role of endoplasmic reticulum stress in Bim-mediated cardiomyocyte apoptosis induced by hypoxia

AIM:To investigate the role of endoplasmic reticulum stress (ERS) in the process of Bim-mediated cardiomyocyte apoptosis induced by hypoxia. METHODS:Cardiomyocytes were isolated from neonatal Sprague-Dawley rats aged 1~3 days, and primarily cultured in vitro. The antibody targeting α-striated muscle actin was used to identify the cardiomyocytes. The siRNAs targeting bim were transfected into cardiomyocytes with liposome, followed by detecting the expression of Bim by Western blotting. Cardiomyocytes were divided into five groups: blank control group, hypoxia group, hypoxia+liposome group, hypoxia+negative control siRNA group and hypoxia+Bim-siRNA group. The cell viability was determined by MTT assay, and the cell apoptotic rate and the intracellular calcium concentration were measured by flow cytometry. The protein expression of caspase-12 and inositol 1,4,5-triphosphate (IP3) was detected by Western blotting. RESULTS:Immunohistochemical identification confirmed that rat cardiomyocytes were successfully cultured. Green fluorescence was observed in the cells transfected with negative control siRNA under fluorescence microscope. The expression of Bim was obviously inhibited after transfected with Bim-siRNAs and the silencing efficiency of Bim-siRNA-2 was the highest (86.73%). Compared with blank control group, the viability of cardiomyocytes in hypoxia group was significantly reduced (P<005). Compared with hypoxia+negative control siRNA group, the viability of cardiomyocytes in hypoxia+Bim-siRNA group was significantly increased (P<005). The apoptotic rate and the intracellular calcium concentration of cardiomyocytes were obviously increased in hypoxia group (P<0.01), and were both decreased after bim silencing (P<005 or P<0.01). The expression of caspase-12 and IP3 was up-regulated in hypoxia group (P<005), and was down-regulated after bim silencing (P<005 or P<0.01). CONCLUSION: Cardiomyocyte apoptosis induced by hypoxia can be inhibited by silencing the expression of bim gene. Caspase-12 and IP3, as markers of ERS, may participate in the process of Bim-mediated cardiomyocyte apoptosis induced by hypoxia.     

Insulin-like growth factor I protects neonatal rat cardiomyocytes from apoptosis through improvement of mitochondrial function

AIM：To investigate whether mitochondrial mechanism is involved in the anti-apoptotic effect of insulin-like growth factor I (IGF-I) on cardiomyocytes. METHODS：Primary neonatal rat cardiomyocytes (NRCMs) were cultured and treated with 200 μmol/L hydrogen peroxide (H2O2) to induce apoptosis. Kruppel-like factor 9 (KLF9)-specific siRNA was transfected into the cells by Lipofectamine 2000. The mitochondrial function was measured by JC-1 mitochondrial membrane potential (MMP) assay. The mitochondrial morphology was observed by transmission electron microscopy. Myocardial cell apoptosis was detected by Annexin V-FITC/PI dual staining, caspase-3 activity assay, DNA-ladder analysis and Hoechst 33258 staining. RESULTS：The apoptosis of NRCMs was induced by H2O2, with MMP decreased by (24.0±1.6)% compared with control group. The fall rates of MMP in IGF-I group and KLF9 siRNA group were (18.3±1.2)% and (15.2±1.2)%, respectively (both P<0.01 vs H2O2 group), and improved mitochondrial morphology, decreased caspase-3 activity, attenuated DNA fragmentation and reduced apoptotic bodies were also observed in these two groups. The apoptotic rates of NRCMs in IGF-I group and KLF9 siRNA group were (22.4±4.2)% and (32.5±3.5)%, respectively, both lower than that in H2O2 group ［(42.5±1.8)%, P<0.01］. The anti-apoptotic effect of KLF9 silencing on NRCMs was consistent with that of IGF-I treatment. CONCLUSION：IGF-I protects NRCMs from apoptosis through down-regulating KLF9 expression and improving mitochondrial function.     

Modulation of bacterial redox protein azurin induces human osteosarcoma cell apoptosis by Fas antigen and caspase-8

AIM: To determine the role of Fas antigen and caspase-8 in modulating apoptosis of osteosarcoma cells induced by bacterial redox protein azurin. METHODS: The human osteosarcoma cell line U2OS was treated with bacterial redox protein azurin (150 mg/L) for 6, 12, 24 and 48 h, respectively. Cell immunohistochemistry and quantitative image pattern analysis were applied for detecting the expression of Fas antigen. Caspase-8 activity was detected using caspase-8 fluorescent assay kit. The apoptotic rate was measured by FCM. RESULTS: Compared with the control group, the expression of Fas antigen and activity of caspase-8 significantly increased in U2OS cells treated with 150 mg/L azurin (P<0.01). There was positive correlation between the expression of Fas antigen and activity of caspase-8 (r=0.873, P<0.01). The increased Fas antigen expression had the function to transfer apoptotic signals and the anti-Fas antibody promoted azurin induced apoptosis through increasing Fas antigen expression. IETD-FMK blocked the activation of procaspase-8 and reduced apoptosis of U2OS cells in the presence of azurin or anti-Fas antibody. The apoptotic rates in azurin group and anti-Fas antibody group were significantly different from the inhibitor group (P<0.01). CONCLUSION: The Fas-dependent signalling is the important pathway of azurin inducing apoptosis in U2OS cells. The up-regulation of csepase-8 may play an important role.     

Effect of puerarin on expression of Fas/FasL mRNA in lung tissue with pulmonary injury induced by ischemia-reperfusion in rabbits

AIM：To investigate the effect of puerarin (Pur) on expression of Fas/FasL mRNA in lung tissue during pulmonary ischemia and reperfusion injury (PIRI) in rabbits.METHODS：Single lung ischemia and reperfusion animal model was used.The rabbits were randomly divided into three groups,sham operated group (sham,n=10),PIR group (I-R,n=30) and PIR+ Pur group (Pur,n=30).Changes of several parameters included apoptotic index (AI),wet to dry ratio of lung tissue weight (W/D) and index of quantitative assessment of histologic lung injury (IQA) were measured at 60,180 and 300 minutes after reperfusion in lung tissue.Meanwhile,the location and expression of Fas/FasL mRNA were observed.Lung tissue was prepared for light microscopic and electron microscopic observation at 60,180,300 minutes after reperfusion.RESULTS：As compared with group I-R,Fas/FasL mRNA slightly expressed in intima and extima of small pulmonary artery,alveoli,and bronchiole epithelia in group Pur.The values of AI,W/D and IQA showed significantly lower than that in group I-R at 60,180,300 minutes after reperfusion in lung tissue (P<0.01 and P<0.05).Meanwhile,abnormal changes of the lung tissue in morphologically were lessen markedly in group Pur.CONCLUSION：Puerarin produces a notable protective effects on PIRI in rabbits by inhibiting Fas/FasL mRNA expression and decreasing apoptosis.     

Relation of Fas/FasL-mediated caspase-3 activation with acinar cell apoptosis in rats with acute pancreatitis

AIM: To observe the expression and interrelationship of apoptosis controlling genes and proteins Fas, FasL, caspase-3 in rats with acute pancreatitis (AP). METHODS: Forty male Sprague Dawley rats were randomly divided into four groups, 10 rats each group. Acute pancreatitis with different inflammatory degree was induced by retroinjecting 2.0%, 3.5% or 5.0% sodium taurocholate at dose of 1 mL/kg body weight into the pancreaticobiliary duct. All the rats were sacrificed 6 h after operation. The pathologic changes of pancreas were observed under optical microscope. The protein and mRNA expressions of Fas, FasL, caspase-3 in pancreatic tissue were measured by Western blotting and RT-PCR. The apoptosis of acinar cells was measured by the methods of in situ end labeling. RESULTS: In normal pancreatic tissue, there appeared the protein and mRNA expression of Fas, FasL, caspase-3. In acute pancreatitis with different inflammatory degree, with the degree of inflammation worsen, the apoptosis cells tapered, the expression of above protein and mRNA also descended gradually. Furthermore, the variation tendency of caspase-3 among the four groups was in coincidence with Fas or FasL. CONCLUSION: Fas/FasL -mediated apoptotic pathway participates in the regulation of acinar cell apoptosis in acute pancreatitis.     

Effect of bim silencing by siRNA on hypoxia-induced apoptosis of rat cardiomyocytes

AIM：To investigate the effect of BH3-only protein Bim (Bcl-2 interacting mediator of cell death) on apoptosis of rat cardiomyocytes induced by hypoxia. METHODS：Rat cardiomyocytes were isolated from infant rats aged 1~3 days and then primarily cultured. The antibody targeting α-actin of striated muscle was used to identify the cardiomyocytes. The siRNAs of bim were transfected into the cardiomyocytes with liposome, and the expression of Bim was determined by Western blotting. The cardiomyocytes were divided into blank control group, hypoxia group, hypoxia+liposome group, hypoxia+negative control siRNA group and hypoxia+bim-siRNA group.The frequency and rhythm of cardiomyocyte beating were observed and recorded under inverted microscope. The activity of lactate dehydrogenase (LDH) in the culture medium was assessed by automatic biochemical analyzer. The viability of the cells was analyzed by MTT assay. The cell apoptotic rate was measured by flow cytometry. The protein expression of Bim, Bax, Bcl-2, p-p38 MAPK and p38 MAPK was detected by Western blotting. RESULTS：Immunohistochemical identification confirmed that the rat cardiomyocytes were successfully cultured. The expression of Bim was obviously inhibited after transfected with bim-siRNAs and the silencing efficiency of bim-siRNA-2 was the highest (86.73%). The frequency of cardiomyocyte beating was slowed down after hypoxia and the rhythm was disordered, while the frequency of beating was obviously increased after silencting the expression of bim. Compared with control group, the LDH in the culture medium was increased (P<0.01), and the viability of the cardiomyocytes was reduced in hypoxia group (P<0.05). The apoptotic rate was increased (P<0.01). After transfection with bim-siRNA, the release of LDH was decreased, and the viability of the cardiomyocytes was increased. The apoptotic rate was decreased. The results of Western blotting showed that hypoxia increased the expression of Bax and p-p38 MAPK (P<0.05), and decreased the expression of Bcl-2 (P<0.01), while transfection with bim-siRNA reduced the effects caused by hypoxia (P<005). These were greatly related to the decrease of apoptosis. However, the expression of p38 MAPK was not changed. CONCLUSION：The apoptosis of cardiomyocytes induced by hypoxia can be inhibited by silencing the expression of bim gene by down-regulation of p-p38 MAPK and Bax expression and up-regulation of Bcl-2 expression.     

Effect of Fas/FasL on late reperfusion of acute myocardial infarction and the potential oxidative stress mechanism in canine

AIM: To discuss the effect of Fas/FasL on the late reperfusion of acute myocardial infarction (AMI) and the potential oxidative stress mechanism. METHODS:Eighteen anesthetized dogs were randomly divided into three groups: late reperfusion group (n=6): ligated the coronary for 6 h, followed by reperfusion for 6 h; permanent ischemia group (n=6): after pericardium were opened for 6 h, ligated the coronary for 6 h, and did not reperfuse; control group (n=6): did not ligate the coronary but operation last for 12 h. Infarction brim myocardial Fas/FasL was detected by immunohistochemistry. Apoptosis index (AI) was detected by TUNEL. SOD and GR activity and MDA content were detected by colorimetry. RESULTS:The expression of Fas/FasL and apoptosis index were significantly higher in permanent ischemia group and late reperfusion group than those in control group (P<0.05, P<0.01), and the difference between them was also significant (P<0.05). SOD and GR activities were lower in permanent ischemia group and late reperfusion group than those in control group (P<0.05, P<0.01). The MDA contents in permanent ischemia group and late reperfusion group were higher than that in control group (P<0.05). CONCLUSION:The late reperfusion of AMI promotes the expression of Fas/FasL and myocardial apoptosis, and it may be due to oxidative stress mechanism.     

Protective effect of quercetin on rat cardiomyocytes against anoxia/reoxygenation injury is mediated by PKCε signaling pathway

AIM：To investigate whether quercetin (Que) protects cardiomyocytes from anoxia/reoxygenation (A/R) injury through protein kinase C epsilon (PKCε) pathway. METHODS：Primary cardiomyocytes were isolated from neonatal SD rats and exposed to A/R (3 h of anoxia followed by 2 h of reoxygenation) as well as Que and/or εV1-2 (a selective PKCε inhibitor) preconditioning. The expression of PKCε in the cells was detected by Western blotting. The levels of lactate dehydrogenase (LDH) and creatine kinase (CK) in cell culture supernatants, the reactive oxygen species (ROS) and mitochondrial membrane potential in the cells, the opening of mitochondrial permeability transition pore (mPTP) and the cell viability and apoptosis were also measured. RESULTS：The expression of PKCε protein was significantly increased in the cardiomyocytes pretreated with 40 μmol/L Que 72 h before A/R (P<0.01 vs A/R group). Meanwhile, Que preconditioning could increase cell survival rate, decrease ROS production and cell apoptosis, alleviate the loss of mitochondrial membrane potential and inhibit the opening of mPTP induced by A/R injury (P<0.01 vs A/R group). However, pretreatment with Que and εV1-2 attenuated these protective effects of Que (P<0.01 vs Que+A/R group). CONCLUSION：One of the mechanisms underlying the cardioprotective effect of Que might be the increase in PKCε protein expression and the activation of its downstream pathway.